Antimony in lead-acid cells. Part I. Analysis of solutions for antimony(III) and antimony(V) and electrodes for antimony

Abstract

Analytical techniques were investigated for the determination of Sb in lead-acid cells. In the range 50–500 p.p.m. of Sb, analysis was possible by volumetric titration with KMnO₄ solution. Below 50 p.p.m. atomic-absorption spectrometry (AAS) was applied and, when used with aqueous solutions, the total Sb was determined. Sb(III) was separated from Sb(V) by complexing with sodium diethyldithiocarbamate at pH 9.5 and extracting the Sb(III) into isobutyl methyl ketone (IBMK); partitioning with a single-stage extraction was excellent. A similar technique for determining the total Sb was evaluated using ammonium tetramethylenedithiocarbamate at pH 2 and again extracting into IBMK. The extraction procedure was used, where appropriate, to increase the concentration of Sb by using a large aqueous volume and a small organic volume. Dissolution of electrodes containing Pb, PbO₂ and PbSO₄ was accomplished by oxidising with sodium hypochlorite and dissolving in a nitric acid-tartaric acid mixture. When totally in solution Sb was stabilised using concentrated HCI and any Sb(III) oxidised to Sb(V) with NaNO₂. The Sb(V) was extracted into IBMK and quantitatively determined using AAS.